I really like an au in which Stanley and Fiddleford are working together in the Shack and Mcgucket kinda looks like Merlin from The Sword in the Stone 1963 (he's adorable I can't)
I like to imagine attractions in Mystery Shack were half fake and the other half were Mcgucket's inventions (Dipper would be amazed by them. By the way, in this au Fiddleford hadn't gone mad so that means he kept his good relationships with his son? Maybe they were building some attractions together and Dipper sometimes was happy to help. Soos were bringing them inspiration :D)
And at one point, Fiddleford would get carried away with space and a "send a message to aliens" attraction appeared in the Shack, in which you could send a message in Morse code (there would be a translator of this very code nearby for an additional fee)
And Fiddleford himself would also have sent several messages, one of which would have been a country song, banjo version, and sent each verse in turn, and the last message was "That'll be $99.9!!" from Stan
(Stan wanted to bet $999, but Fidds secretly put a dot on it, because he's a sweet honeybun and doesn't want to steal from an alien race. Steal too much, ahem)
(Stanley noticed everything, but pretended not to see anything)